“No matter how much you drink it’s not going to prevent you from getting heat stroke,” Maeda says.

If a person shows symptoms of heatstroke – weakness, dizziness, headache, nausea, confusion or irrational behavior – Maeda says it is most important to cool them down as quickly as possible rather than giving them fluids. He recommends moving them to the shade, putting ice packs on the neck or under the arm or even submerging them in an ice bath.

Maeda adds people who pass out in the heat are typically not dehydrated; they are affected by the heat or possibly a cardiovascular concern.

Humidity is more important than heat

Your body’s core temperature is not only affected by the temperature, Maeda says, it is even more influenced by humidity. That’s because on muggy days, sweat does not dry quickly so your body cannot cool off.

“Dry heat is much more tolerable than having a hot and humid day like Sunday.”

Water is not always best

Dr. Tony Woodward, director of emergency medicine at Seattle Children’s Hospital, says anyone who is playing or exercising in the heat will be better off drinking a beverage with electrolytes – such as a sports drink – rather than plain water. If you’re sweating a lot and only drinking water, Woodward says you need to replace the lost sodium in your body so your electrolytes are not dangerously low.

But if you’re taking it easy in the heat, Woodward says plain water is just fine. He adds cold water will hydrate you more quickly and pass through your digestive system faster.

Sugary drinks like soda take longer to digest, so Woodward does not recommend those beverages on warm days.

You can drink too much

While it is important to stay hydrated when it is hot out, Maeda says it’s also possible to drink too much water, diluting your sodium level.

“Drink to thirst,” Maeda says. “That way you avoid over hydrating.”

Still, Woodward recommends people watch for signs of dehydration in themselves and their children, including dry mouth, lack of tears or saliva, dark-colored urine or racing heartbeat.

Kids won’t tell you when they’re thirsty

Woodward says parents need to keep track of how much their children are drinking and how long they’re in the sun.

“Kids don’t say ‘I’m dehydrated, help me,’ they have vague symptoms like irritability,” he says. “Parents need to make sure kids drink enough because the kids are going to be focused on the activity they’re doing.”

Parents should especially be conscious of infants, who have no control over their environment, Woodward says. He urges parents to never leave children alone in a car or other hot place.